Connector plate



Sept. 26, 1967 G. A. KOENIGSHOF CONNECTOR PLATE Filed July 29, 1965 4 E g A 3 g A QFQPQQQFQ SSS Q wbwwwwwb p E p Q dwwqdwdy g United States Patent 3,343,439 CONNECTOR PLATE Gerald A. Koenigshof, Kensington, Md., assignor to Timber Engineering Company, a corporation of Delaware Filed July 29, 1965, Ser. No. 475,632 6 Claims. (Cl. 8513) This invention relates to connector plates and more particularly, to connector plates for securing together wood structural members.

Connector plates are commonly used for securing together abutting wood members to form structures, such as wood roof trusses that are used in the construction of buildings. The wood members are arranged in co-planar, abutting relation and a connector plate is secured to the wood members and extends over the joint. Usually, connector plates are provided on opposite sides of the wood members. The connector plates have teeth which are struck from the plate and project outwardly on one side of the plate. The teeth are driven into the wood members simultaneously by means of a press. The connector plates are rigidly fastened to the Wood members by the nail-like teeth and transmit forces between the wood members. Additional fasteners, such as nails, are not normally used with the connector plates for fastening together the wood members.

One deficiency of conventional connector plates is that the teeth have a tendency to pull back out of the wood members when the joint is stressed. Wood roof trusses that are fabricated using conventional connector plates are subject to transverse bending of the truss during handling and transporting which may cause the plates to break loose from the wood members, and the truss either comes apart, or the strength of the truss is diminished to the point where it is unsatisfactory for use.

It is important for the connector plates to have a maximum tensile strength per unit of cross sectional area, but when the teeth are struck from the plate, the metal removed in forming the teeth reduces the net unit cross sectional area of the plate and substantially reduces the tensile strength of the plate. However, a large number of teeth are important to assure that the stress in the wood members is transmitted to the connector plate and to cause the connector plate to be tightly secured to the wood members. Conventional connector plates usually represent a compromise between obtaining the maximum tensile strength per unit cross sectional area and providing a maximum number of teeth.

Another problem encountered with conventional connector plates is that the teeth may not provide sutficient gripping action in the wood to prevent the connector plate from being pulled out of the wood members when it is under stress. Also, when trusses are fabricated from green lumber, the wood fibers tend to push the teeth of the connector plate back out of the wood member, as the wood dries out. If the teeth are made relatively long in relation to their width in order to increase the gripping surface, they have a tendency to buckle when the plate is being pressed into the wood members, particularly if the wood is dense. When a tooth buckles, it interferes with the connector plate being pressed fiat against the face of the wood member, and instead of providing additional gripping action for the plate, the buckled tooth reduces the net cross sectional area of the plate.

The wood structural members of a truss intersect at various angles with respect to each other. The Wood grain runs generally longitudinally of the member and fiat teeth as commonly used in connector plates are more easily inserted with the wide faces of the teeth parallel to the wood grain. The teeth tend to separate the wood fibers and pass between them rather than to sever the fibers as would teeth which extend across the grain. It is preferable for the teeth to cut the wood fibers, since the severed fibers become wedged against the faces of the teeth and resist withdrawal of the teeth. The difficulty in orienting the teeth on the plate, however, is that the structural members are arranged in various angular relations to the connector plate and the orientation of the teeth with respect to the Wood grain of the structural members cannot be predetermined.

In view of the defects of conventional connector plates, it is an object of this invention to provide a connector plate which resists being pulled out of the wood members when the joint is under stress.

It is a further object of this invention to provide a truss plate having a maximum number of teeth, while at the same time having relatively high tensile strength per unit cross sectional area.

It is a still further object of this invention to provide a connector plate which transmits maximum stress between wood members regardless of the direction of wood grain in the wood members.

These objects are accomplished in accordance with the preferred embodiment of the invention by a connector plate in the form of a flat metal plate having teeth individually struck from the plate. The teeth are bent out on one side of the plate and arranged in rows extending in the opposite direction from the shank of adjacent teeth of the row. The teeth are elongated and are inclined laterally in an upright plane with respect to the plane of the plate. Each tooth at its free end is bent outwardly from the opening in the plate and the rounded point of the tooth is offset away from the direction of incline of the tooth. Also, the wide, flat sides of each tooth are arranged at an acute angle with respect to the adjacent teeth.

This preferred embodiment is ilustrated in the accompanying drawings, in which:

FIG. 1 is a top plan view of the connector plate of this invention;

FIG. 2 is a cross sectional view of the connector plate along the line 2-2 in FIG. 1;

FIG. 3 is an enlarged cross sectional view of the connector plate along the line 3-3 in FIG. 1; and

FIG. 4 is an enlarged cross sectional view of the connector plate along the line 44 in FIG. 1. I

Referring to FIGS. 1 and 2, the connector plate of this invention includes a substantially flat sheet 2. The sheet 2 has perforations 4 at a plurality of locations to form teeth 6 from the sheet 2. Each perforation is in the form of an irregular loop, so that the metal in the center of the loop is attached to the sheet 2 -only across the ends of the loop. Each of the loop portions is bent outwardly on one side of the plate to form a tooth 6, as shown in FIG. 2. The perforations are arranged in rows 8 and 10,

' which are typical of the rows of perforations in the sheet 2. Fewer teeth are provided in the first row 8 and they are offset from the teeth in the second row 10. Each perforation has a base extending across the end of the loop of the perforation 4 and each tooth 6 is connected to the sheet 2 along the base of the perforation. As shown in FIG. 1, alternate perforations 4 in the same row have a base 12 extending substantially in the same direction and obliquely to the longitudinal axis of the row 8. Also, alternate teeth face in the same direction, while adjacent teeth face in opposite directions. The bases 14 of the other teeth in the row 8 extend. obliquely to the axis of the row 8 at a substantially equal but opposite angle from the base 12. Preferably, the baseslZ at an angle of about 20.

In the second row 10, the first perforation 4 has a base 16 which is substantially parallel to the base 14 of the alternate teeth in the first row 8, although the loop of the perforation extends in the opposite direction from that of the alternate teeth in the first row 8. The alternate teeth in the rows 8 and 10 are offset with respect to the longitudinal axis of the row and are also offset with respect to the teeth in adjacent rows.

Since the base of each tooth extends obliquely to the transverse axis of the sheet 2, the teeth are inclined with respect to the plane of the sheet 2, as shown in FIGS. 2 and 3. The orientation of the bases 12, -14 and 16 with respect to the longitudinal axes of the rows 8 and 10 determines whether the tooth 6 will be inclined in one direction or the other when the tooth is bent outwardly from the sheet 2.

Typical teeth are illustrated in FIGS. 3 and 4. Each tooth has a root portion 18, a shank portion 20, and an end portion 22. The teeth have a substantially greater width than thickness. The root portion 18 has sloping lateral edges and the opposite edges of the shank portion 20 are substantially parallel to each other. The longitudinal axis of the shank portion is inclined with respect to the plane of the sheet 2. The tooth 6 is inclined both in the plane of'the wide faces of the shank portion 20 and also in the plane of the lateral edges, as shown in FIG. 4. The end portion 22 of the tooth is generally in the form of a right triangle with the rounded point 24 of the tooth being offset from the longitudinal axis of the shank portion 20. The end portion 22 is bent along the line separating the shank portion and the end portion, so that it is inclined in the opposite direction from that of the shank portion 20 and the root portion 18, as shown in FIG. 4.

The shape and orientation of each tooth with respect to the sheet 2 causes the tooth 6 when pressed into a wood member to be deflected laterally by the force of the wood fibers against the longer lateral edges of the shank portion 20 and of the root portion 18, which are the left hand lateral edges, as viewed in FIG. 3. At the same time that the tooth 6 is being deflected laterally, it is also being deflected generally in the direction of the slope of the end portion 22 by the force of the wood fibers on the face of the end portion. Since the rounded point 24 is offset from the longitudinal axis of the shank portion 20, there is a tendency for the tooth to twist as it is being pressed into the wood member. Furthermore, as shown in FIG. 1, the teeth in the same row have different orientations with respect to the longitudinal axis of the row. This feature, in combination with the outwardly bent end portion of each tooth, causes the teeth to sever some of the wood fibers regardless of the orientation of the sheet 2 with respect to the woodgrain in the structural member.

The connector plate of this invention has teeth of a particular shape that causes them to be twisted when pressed into wood members. When the connector plate is applied across a joint in a roof truss, for example, the teeth are so tightly secured in the wood that the roof truss can be subjected to lateral forces during transporation and erection without causing the teeth to pull out of the wood. By offsetting the teeth in the rows and utilizing inclined teeth, the plate maintains a high tensile strength, although a large number of teeth are punched from the plate. The inclined teeth provide an enlarged area of contact with the wood fibers, without a corresponding decrease in the cross sectional area of the sheet 2.

While this invention has been illustrated and described in one embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims.

I claim:

1. A connector plate for joining together abutting wood members comprising:

a sheet having a plurality of openings therein, each opening having a single tooth projecting therefrom, said tooth projecting from one side of each opening, said one side being substantially straight, said openings being in the shape of the profile of the tooth and being arranged in a plurality of rows,

said tooth having a root portion joined to the sheet and a shank portion joined to the root portion and an end portion joined to the shank portion,

said root portion being substantially fiat and being wider than said shank portion and end portion, said root portion having opposite edges converging toward said shank portion, one of said root portion edges having a greater length than the opposite root portion edge,

said shank portion having a substantially greater width than thickness and a substantially uniform width, said root and shank portions being angularly inclined toward said opening with respect to the plane of said sheet, said end portion being angularly inclined away from said opening with respect to the plane of said sheet,

said end portion having opposite edges, one of said end portion edges being a continuation of said shank edge adjacent said one root portion edge and the other of said end portion edges being inclined at an acute angle with respect to said one end portion edge to define a penetrating point,

said opening having a longitudinal axis extending substantially parallel to the edges of the opening which correspond to said shank portion, said straight side defining an axis intersecting said longitudinal axis at an acute angle, whereby the tooth is deformed upon being inserted in wood members and resists withdrawal.

2. The connector plate according to claim 1 wherein said longitudinal axes of said openings in each row are approximately parallel, said straight side of alternate openings in a row are at the same end of the opening and the straight sides of adjacent openings in a row are at opposite ends of the openings.

3. The connector plate according to claim 2 including a second row of said openings adjacent the first mentioned row of openings, said straight sides of alternate openings in said second row being at the same end of said openings and said straight sides of adjacent openings in said second row being at the opposite ends of said openings, straight sides of said adjacent openings in said first and second rows defining axes converging toward one end of said first row.

4. The connector plate according to claim 3 wherein said first and second rows are substantially parallel, straight sides of adjacent openings in said first row converging toward one end of said first row and straight sides of adjacent openings in said second row converging toward the opposite end of said second row.

5. The connector plate according to claim 4 wherein said openings of said first row are laterally offset from said openings in said second row.

6. The connector plate according to claim 3 wherein said converging straight sides define axes which intersect at an acute angle of about 20 degrees.

References Cited UNITED STATES PATENTS 272,685 2/1883 Hart 11 3,090,088 5/1963 Foley et a1. 85l3 3,211,043 10/1965 Sandford 8513 CARL W. TOMLIN, Primary Examiner.

THOMAS P. CALLAGHAN, Examiner.

R. S. BRITTS, Assistant Examiner. 

1. A CONNECTOR PLATE FOR JOINING TOGETHER ABUTTING WOOD MEMBERS COMPRISING: A SHEET HAVING A PLURALITY OF OPENINGS THEREIN, EACH OPENING HAVING A SINGLE TOOTH PROJECTING THEREFROM, SAID TOOTH PROJECTING FROM ONE SIDE OF EACH OPENING, SAID ONE SIDE BEING SUBSTANTIALLY STRAIGHT, SAID OPENINGS BEING IN THE SHAPE OF THE PROFILE OF THE TOOTH AND BEING ARRANGED IN A PLURALITY OF ROWS, SAID TOOTH HAVING A ROOT PORTION JOINED TO THE SHEET AND A SHANK PORTION JOINED TO THE ROOT PORTION AND AN END PORTION JOINED TO THE SHANK PORTION, SAID ROOT PORTION BEING SUBSTANTIALLY FLAT AND BEING WIDER THAN SAID SHANK PORTION AND END PORTION, SAID ROOT PORTION HAVING OPPOSITE EDGES CONVERGING TOWARD SAID SHANK PORTION, ONE OF SAID ROOT PORTION EDGES HAVING A GREATER LENGTH THAN THE OPPOSITE ROOT PORTION EDGE, SAID SHANK PORTION HAVING A SUBSTANTIALLY GREATER WIDTH THAN THICKNESS AND A SUBSTANTIALLY UNIFORM WIDTH, SAID ROOT AND SHANK PORTION BEING ANGULARLY INCLINED TOWARD SAID OPENING WITH RESPECT TO THE PLANE OF SAID SHEET, SAID END PORTION BEING ANGULARLY INCLINED AWAY FROM SAID OPENING WITH RESPECT TO THE PLANE OF SAID SHEET, SAID END PORTION HAVING OPPOSITE EDGES, ONE OF SAID END PORTION EDGES BEING A CONTINUATION OF SAID SHANK EDGE ADJACENT SAID ONE ROOT PORTION EDGE AND THE OTHER OF SAID END PORTION EDGES BEING INCLINED AT AN ACUTE ANGLE WITH RESPECT TO SAID ONE END PORTION EDGE TO DEFINE A PENETRATING POINT, SAID OPENING HAVING A LONGITUDINAL AXIS EXTENDING SUBSTANTIALLY PARALLEL TO THE EDGES OF THE OPENING WHICH CORRESPOND TO SAID SHANK PORTION, SAID STRAIGHT SIDE DEFINING AN AXIS INTERSECTING SAID LONGITUDINAL AXIS AT AN ACUTE ANGLE, WHEREBY THE TOOTH IS DEFORMED UPON BEING INSERTED IN WOOD MEMBERS AND RESISTS WITHDRAWAL. 